The present invention is directed to an electroplating apparatus for plate-shaped workpieces which are treated as they are passed horizontally through the apparatus and along a plating path. The apparatus includes a plurality of contact posts which are arranged at a distance from one another and offset from the center of the path for movement along the path together with the workpiece for cathodic contacting of the workpieces. The apparatus is provided with an arrangement for supplying cathode current to the contact posts by at least one live rail having contact springs, which contact the post on the basis of a wiper contact.
An electroplating apparatus wherein a plate-shaped workpiece, such as a printed circuit board is moved in a horizontal path through the apparatus is disclosed in my U.S. Pat. No. 4,755,271, whose disclosure is incorporated by reference and which claims priority from German Application No. 36 25 483, which was the basis for European Application No. 0 254 962. In the arrangement of this patent, the workpiece to be electroplated, in particular a printed circuit board, was conducted in a horizontal throughput path through a treatment cell that contains an electrolyte solution. In order to guarantee a reliable cathodic contacting of the moving workpiece, at least one forceps-shaped contacting post which is movable along the path, together with the workpiece, is provided. An endless drive is preferably provided as a displaceable carrier for a plurality of the contact posts, which are arranged at a distance from one another. Thus, the drive also serves as means for conveying the workpiece through the treatment cell. In one of the embodiments set forth in the above-mentioned U.S. Patent, an upper and lower toothed belt are provided and support posts on which the clamping jaws are carried and the clamping jaws are supplied with the cathode current by brushes.
In an electroplating device disclosed in published German OS No. 36 24 481, a plate-shaped workpiece is treated as it moves in a horizontal path, and a supply of cathode current to the contact posts or clamps, which are carried by endless belts or chains, also occurs by a stationary brush arrangement that presses against the contact posts or clamps.
The cathodic contacting of plate-shaped workpieces set forth above is far less sensitive to contact with electrolyte solutions than are roller contacts and wire contacts. In view of the required displaceability of the contact posts or clamps, however, a power transmission between the stationary and moving parts continues to be required, whereas the corresponding contacting can now be displaced into an area that is protected against the access of electrolyte solution and other negative influences.
Given electroplating with current densities of, for example, 10 A/dm.sup.2 and more, a high thermal load occurs in the region of the power transmission between resting and moving parts. Particularly given the employment of brush arrangements, the brushes ar highly heated when subjected to such current densities so that a premature wearing of these brushes will occur.